Ten Regional Transmission Organizations (RTOs) operate bulk electric power systems across much of North America. RTOs are independent, membership-based, non-profit organizations that ensure reliability and optimize supply and demand bids for wholesale electric power. In 2009, U.S. RTOs managed 60% of the power supplied to load-serving entities. In other parts of the country, electricity systems are operated by individual utilities or utility holding companies.

RTOs first developed in the 1990's to accommodate the Federal Energy Regulatory Commission's (FERC) policy to encourage competitive generation through requiring open access to transmission. In the Northeast, the RTOs evolved from power pools that had coordinated utility operations for many decades. Elsewhere (the Midwest, California and Texas), RTOs grew up to meet both State and federal policies on competitive generation and open transmission access.

Integrated utilities that combine generation, transmission and distribution functions, and

Other entities such as power marketers and energy traders.

RTOs dispatch power by feeding both day-ahead and real-time bids from both generators and load-serving entities into complex optimization software, along with other information like unit characteristics. They post voluminous price data for thousands of locations on the system at time intervals as short as five minutes.

Those interested in more information about RTOs can follow the links below to RTOs' websites and look at the FERC daily summaries of RTO day-ahead and real-time prices.